Electrical plug contacts



Sept. 2, 1969 S. T. DEAKIN ELECTRICAL PLUG CONTACTS Filed April 10, 1967 United States Patent US. Cl. 339-150 2 Claims ABSTRACT OF THE DISCLOSURE An electric plug contact comprises a split tube with resilient ears, forming the contact surfaces, folded back from the edge of the split to lie around the outside of the tube. Two or more such contacts may be held on an insulating stem. The contact, or one of them, may receive a diode or other electrical device.

The invention relates to electrical plug contacts and provides a plug contact comprising a piece of resilient sheet or strip metal bent to tubular form with a longitudinal opening or joint along one side and having at one, and preferably each, side of the opening or joint a portion of the strip or sheet bent back to lie around, but spaced from, the external surface of the tube to provide a resilient radially deformable contact surface.

In one form of the invention the tube has, along 1ts length, two or more independent portions bent back as aforesaid to provide independently deformable contact surfaces.

The invention also provides an electrical plug having a contact as above defined surrounding, and carried by, a stem of insulating material. There may be two or more such contacts along the stern and electrically insulated from one another or electrically connected through an electrical device such as a lamp or a diode. The contact or contacts may be attached to the stern by inwardly projecting tongues or protuberanceson the tube engaging in slots or recesses in the stem or vice versa.

There may be a connecting tag at one end of the tube' and the tag may be bent inwardly to extend to, or nearly to, the axis of the tube for attachment of a central wire.

Some specific embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a perspective view of a single plug contact,

FIGURE 2 is a perspective view of a double contact or shorting pin,

FIGURE 3 shows an insulating stem or finger grip for the contact of FIGURE 2,

FIGURE 4 shows a plug incorporating two contacts and an electrical device, the figure including a cover shown detached,

FIGURE 5 shows, separated, the parts of an alternative form of plug, and

FIGURE 6 is a similar view of a third form of a plug.

Referring first to FIGURE 1 the contact is formed by bending a blank of sheet or strip metal (e.g. beryllium copper) to tubular form 10 leaving an opening or gap 11 and reversely bending two ears or extensions 12 to overlie the outside of the tubular portion but spaced slightly therefrom. The ears extend round to the back of the tube to leave a gap between the ears of a width about equal to that of the gap 11. The ears provide resilient contact surfaces for engagement in a socket and ice may be compressed without substantial deformation of the tube 10. A connection tag 14 extends from one end of the tube.

FIGURE 2 shows a double contact which may be used as a shorting pin in a selector board such as that described in British patent specification No. 934,627, the two contact parts engaging respectively in the socket contacts of the two sets. The double contact has a single tubular portion 19 with an opening 20 and two pairs of contact ears 21, 22 each as in FIGURE 1, the ears of each pair being compressible independently of the' ears of the other pair. The lower end of the tubular portion is domed at 23 and the upper end is notched at 25 to receive and hold a projection 26 on an insulating stem or finger grip 27 (FIGURE 3).

The plug shown in FIGURE 4 comprises a contact 30 as in FIGURE 1 mounted on an insulating stem 31 and retained between ribs 32 on the stern. There is also a contact 33 on the stem, this contact being similar to the portion 22, 23 of FIGURE 2. The contact is held by soldering to a centre conductor 35 moulded in the stern. At the upper end there is a lamp or diode 36 having connections to the conductor 35 and the tag 14. A resilient plastic cover 37 is provided and is held in place by projections 38 snapped under the upper rib 32. The plug may be used in a board as described in British patent specification No. 934,627 to connect the lamp or diode into a circuit.

In the construction shown in FIGURE 5 there is a tubular portion 40 with cars 41 as described above. The tubular portion is extended and enlarged to provide a housing 42 for a diode or other device. An insulating stem 43 with a head 44 is inserted into the portion 40, before folding over of the end 45, and the head 44 seats on the part 46. Tags 47 on the end of the tubular portion engage in recesses 48 in the stem to hold the stem in place. On the lower end of the stem there is a second contact 50 which is held by tags 57 engaging in notches 52. This contact has a connection tag 53 bent inwardly to lie under the end of a groove 54 in the stem. In use a connecting wire from a device within the housing is threaded down the groove and soldered to the tag 53.

The construction shown in FIGURE 6 is similar to that just described except that the insulating stern 43a is held by three stake points or pips 55 produced after assembly and the contact 50a is retained on the stem by the connecting wire soldered to the end of the contact at 56.

Although the above plugs may, as stated, be used in a selector board of the construction disclosed in British specification No. 934,627 in which the socket contacts are resilient, they are also suitable for use in selector boards in which the socket contacts have little or not resilience.

I claim:

1. An electric plug comprising a stem of electrical insulating materials and two tubular plug contacts threaded over the stem and spaced apart along the length of the stem, the contacts each comprising a thin walled cylindrical metal tube with a longitudinal gap along one side and two resilient ears attached to the edges of the gap and extending partway around the outside of the tube in spaced relation thereto towards the opposite side thereof and at least one of the contacts having at least one internal tongue engaging in a recess in the stem to hold the contact in place thereon.

2. An electric plug comprising a stem and two tubular plug contacts threaded over a part of the stem, the contacts each comprising a thin-walled cylindrical metal tube with a longitudinal gap along one side and two resilient ears attached to the edges of the gap and extending partway around the outside of the tube in spaced relation 3 4 thereto towards the opposite side of the tube from the FOREIGN PATENTS said gap, and at least one of said tubes and said stem 1,363,070 4 1 4 Franw having cooperating means retaining the tube against rela- 539 571 9 1941 Great B i i tive axial movement comprising a projection on one of 645,423 11/1950 Great Britain. the parts engaging in the recess of the other. 5

MARVIN A. CHAMPION, Prlmary Examlner References Cited P. A. CLIFFORD, Assistant Examiner UNITED STATES PATENTS 3,208,029 9/1965 Leslie. 33918,147,252

US. Cl. X.R. 

